com.webobjects.directtoweb
Class Rule

java.lang.Object
  com.webobjects.directtoweb.Rule

All Implemented Interfaces:

EOKeyValueArchiving, Serializable

public class Rule
extends Object
implements Serializable, EOKeyValueArchiving

The Rule class represents a simple inference.

A rule consists of a left-hand side and right-hand side. The left-hand side is a set of pre-conditions, represented by a qualifier. The right-hand side is a post-condition, represented by an assignment.

One rule may take precendence over another, depending on authorship, context, and fit. In general, a more specific rule has higher priority.

The D2WModel class makes extensive use of rules.

The implementation is subject to change in future releases.

See Also:

D2WModel, Assignment, EOQualifier, Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from interface com.webobjects.eocontrol.EOKeyValueArchiving

EOKeyValueArchiving.Awaking, EOKeyValueArchiving.FinishInitialization, EOKeyValueArchiving.Support

Field Summary

static String	authorKey A key representing the author.
static String	lhsKey A key representing the left-hand side.
static String	rhsKey A key representing the right-hand side.

Constructor Summary

Rule()
Creates an instance of Rule.

Rule(int author, EOQualifier lhs, Assignment rhs)
Creates an instance of Rule with the specified author, left-hand side, and right-hand side.

Method Summary

int	author() Gets the author.
boolean	canFireInContext(D2WContext context) Indicates whether the rule can fire by evaluating the left-hand side with the specified context.
int	compareRules(Rule otherRule) Compares two rules, based on priority.
Assignment	createAssignment(String keyPath, String value) Creates an assignment with the specified key path and value.
Vector	dataTypesInvolved() Gets the set of names of data types involved.
static Object	decodeWithKeyValueUnarchiver(EOKeyValueUnarchiver unarchiver)
Vector	dynamicPagesInvolved() Gets the set of names of dynamic pages involved.
void	encodeWithKeyValueArchiver(EOKeyValueArchiver archiver) Asks the receiver to archive its state into the EOKeyValueArchiver archiver.
Object	fire(D2WContext context) Fires the right-hand side with the specified context.
String	firstDynamicPageNameInvolved() Gets the name of the first dynamic page involved.
String	firstEntityInvolved() Gets the name of the first entity involved.
String	firstPropertyKeyInvolved() Gets the name of the first property key involved.
String	firstTaskInvolved() Gets the name of the first task involved.
boolean	hasSameSettingsAs(com.apple.client.directtoweb.common.Settings settings, boolean areSettingsForADynamicPage) Compares the rule with the specified settings.
boolean	isEntityPermissionRule() Indicates that a rule involves the assignment of an entity permission.
boolean	isEntityRule() Indicates that a rule involves the assignment of an entity.
boolean	isLookRule() Indicates that a rule involves the assignment of a look.
boolean	isStartupRule() Indicates that a rule involves the assignment of a start-up task or start-up entity name.
boolean	isTaskRule() Indicates that a rule involves the assignment of a task.
EOQualifier	lhs() Gets the left-hand side.
int	priority() Gets the priority of the rule.
Assignment	rhs() Gets the left-hand side.
String	rhsKeyPath() Gets the key path of the right-hand side.
int	rhsKeyPathHash() Gets the hashcode of the key path of the right-hand side.
void	setLhs(EOQualifier newValue) Sets the left-hand side to the specified value.
void	setRhs(Assignment newValue) Sets the right-hand side to the specified value.
Vector	tasksInvolved() Gets the set of names of tasks involved.
String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

lhsKey

public static final String lhsKey

A key representing the left-hand side.

In the current implementation, the value is "lhs".

The implementation is subject to change in future releases.

See Also:

Constant Field Values

rhsKey

public static final String rhsKey

A key representing the right-hand side.

In the current implementation, the value is "rhs".

The implementation is subject to change in future releases.

See Also:

Constant Field Values

authorKey

public static final String authorKey

A key representing the author.

In the current implementation, the value is "author".

The implementation is subject to change in future releases.

See Also:

Constant Field Values

Constructor Detail

Rule

public Rule()

Creates an instance of Rule.

In the current implementation, the default author is DIRECT_2_WEB, and both the left-hand side and right-hand side remain unassigned. Note: A rule should not be used before the right-hand side is set.

The implementation is subject to change in future releases.

See Also:

DIRECT_2_WEB, Rule(int, EOQualifier, Assignment)

Rule

public Rule(int author,
            EOQualifier lhs,
            Assignment rhs)

Creates an instance of Rule with the specified author, left-hand side, and right-hand side.

The interface is subject to change in future releases.

Parameters:

author - instance of Assignment

lhs - instance of EOQualifier

Throws:

IllegalArgumentException - if right-hand side is null

See Also:

Rule(), EOQualifier, Assignment

Method Detail

decodeWithKeyValueUnarchiver

public static Object decodeWithKeyValueUnarchiver(EOKeyValueUnarchiver unarchiver)

encodeWithKeyValueArchiver

public void encodeWithKeyValueArchiver(EOKeyValueArchiver archiver)

Description copied from interface: EOKeyValueArchiving

Asks the receiver to archive its state into the EOKeyValueArchiver archiver.

Specified by:

encodeWithKeyValueArchiver in interface EOKeyValueArchiving

Parameters:

archiver - the EOKeyValueArchiver

See Also:

EOKeyValueArchiver

author

public int author()

Gets the author.

Returns:

int that represents the author

lhs

public EOQualifier lhs()

Gets the left-hand side.

Returns:

instance of EOQualifier

See Also:

setLhs(EOQualifier)

setLhs

public void setLhs(EOQualifier newValue)

Sets the left-hand side to the specified value.

Parameters:

newValue - instance of EOQualifier

See Also:

lhs()

rhs

public final Assignment rhs()

Gets the left-hand side.

Returns:

instance of Assignment

See Also:

setRhs(Assignment)

setRhs

public void setRhs(Assignment newValue)

Sets the right-hand side to the specified value.

Parameters:

newValue - instance of Assignment

See Also:

rhs()

rhsKeyPath

public final String rhsKeyPath()

Gets the key path of the right-hand side.

Returns:

the right-hand side key path.

See Also:

rhs(), Assignment#keyPath()

rhsKeyPathHash

public int rhsKeyPathHash()

Gets the hashcode of the key path of the right-hand side.

The current implementation caches the value of the hashcode.

The implementation is subject to change in future releases.

Returns:

the right-hand side key path hashcode

See Also:

rhsKeyPath(), Object.hashCode()

toString

public String toString()

Overrides:

toString in class Object

canFireInContext

public boolean canFireInContext(D2WContext context)

Indicates whether the rule can fire by evaluating the left-hand side with the specified context.

Parameters:

context - instance of D2WContext

Returns:

true if the rule can fire in the specified context; false otherwise

See Also:

lhs(), EOQualifier.evaluateWithObject(Object)

fire

public Object fire(D2WContext context)

Fires the right-hand side with the specified context.

Parameters:

context - instance of D2WContext

Returns:

the value returned by firing the right-hand side

See Also:

rhs(), Assignment#fire(D2WContext)

createAssignment

public Assignment createAssignment(String keyPath,
                                   String value)

Creates an assignment with the specified key path and value. Creates an instance of Assignment if the value starts and ends with a quotation mark; an instance of KeyValueAssignment otherwise.

Parameters:

keyPath - the key path

value - the value

Returns:

instance of Assignment

See Also:

Assignment#Assignment(String, Object)

priority

public int priority()

Gets the priority of the rule. Priority is largely a function of authorship and how specific a rule is.

The current implementation caches the value of the priority. A "dummy true" rule has low priority. Dynamic page rules have priority over others. A complex EOAndQualifier is higher than a simple one.

The implementation is subject to change in future releases.

Returns:

int representing the priority of the rule

See Also:

author(), D2WModel#DummyTrueKey, EOQualifier

compareRules

public int compareRules(Rule otherRule)

Compares two rules, based on priority.

Parameters:

otherRule - instance of Rule

Returns:

the value 0 if the argument rule is equal to this rule; a value less than zero if this rule is greater than the rule argument; a value greater than zero if this rule is less than the rule argument or the rule argument is null

See Also:

priority()

tasksInvolved

public Vector tasksInvolved()

Gets the set of names of tasks involved.

The current implementation caches the names. Traverses the left-hand side, looking at EOKeyValueQualifiers that specify a task, for example, task="Edit".

The implementation is subject to change in future releases.

Returns:

instance of java.util.Vector

See Also:

lhs(), D2WModel#TaskKey, firstTaskInvolved()

dynamicPagesInvolved

public Vector dynamicPagesInvolved()

Gets the set of names of dynamic pages involved.

The current implementation caches the names. Traverses the left-hand side, looking at EOKeyValueQualifiers that specify a dynamic page.

The implementation is subject to change in future releases.

Returns:

instance of java.util.Vector

See Also:

firstDynamicPageNameInvolved(), lhs(), D2WModel#DynamicPageKey

firstTaskInvolved

public String firstTaskInvolved()

Gets the name of the first task involved.

The current implementation caches the name. Traverses the left-hand side, looking for the first EOKeyValueQualifier that specifies a task.

The implementation is subject to change in future releases.

Returns:

instance of String

See Also:

tasksInvolved(), lhs(), D2WModel#TaskKey

firstPropertyKeyInvolved

public String firstPropertyKeyInvolved()

Gets the name of the first property key involved.

The current implementation caches the name. Traverses the left-hand side, looking for the first EOKeyValueQualifier that specifies a property key.

The implementation is subject to change in future releases.

Returns:

instance of String

See Also:

lhs(), D2WModel#PropertyKeyKey

firstDynamicPageNameInvolved

public String firstDynamicPageNameInvolved()

Gets the name of the first dynamic page involved.

The current implementation caches the name. Traverses the left-hand side, looking for the first EOKeyValueQualifier that specifies a dynamic page.

The implementation is subject to change in future releases.

Returns:

instance of String

See Also:

dynamicPagesInvolved(), lhs(), D2WModel#DynamicPageKey

firstEntityInvolved

public String firstEntityInvolved()

Gets the name of the first entity involved.

The current implementation caches the name. Traverses the left-hand side, looking for the first EOKeyValueQualifier that specifies an entity.

The implementation is subject to change in future releases.

Returns:

instance of String

See Also:

lhs()

dataTypesInvolved

public Vector dataTypesInvolved()

Gets the set of names of data types involved.

The current implementation caches the names. Traverses the left-hand side, looking at EOKeyValueQualifiers that specify a class name.

The implementation is subject to change in future releases.

Returns:

instance of java.util.Vector

See Also:

lhs()

hasSameSettingsAs

public boolean hasSameSettingsAs(com.apple.client.directtoweb.common.Settings settings,
                                 boolean areSettingsForADynamicPage)

Compares the rule with the specified settings. Looks only at the first dynamic page involved if the specified flag areSettingsForADynamicPage is true; looks at the first task involved and first entity involved otherwise.

If areSettingsForADynamicPage is true, it returns true if firstDynamicPageNameInvolved equals the dynamicPage of settings; false otherwise.

If areSettingsForADynamicPage is false, it returns true if firstTaskInvolved and firstEntityInvolved equal the task and entity (respectively) of settings.

The current implementation assumes that the rule is of the form (task="xx" and entity="yy"); no EOOrQualifiers.

The implementation is subject to change in future releases.

Parameters:

settings - instance of Settings

areSettingsForADynamicPage - boolean

Returns:

see method description

See Also:

firstDynamicPageNameInvolved(), firstTaskInvolved(), firstEntityInvolved()

isStartupRule

public boolean isStartupRule()

Indicates that a rule involves the assignment of a start-up task or start-up entity name.

Returns:

true if the rule is a start-up rule; false otherwise

See Also:

rhs(), D2WModel#StartupTaskKey, D2WModel#StartupEntityNameKey, D2WContext#startupTask(), D2WContext#startupEntityName()

isLookRule

public boolean isLookRule()

Indicates that a rule involves the assignment of a look.

Returns:

true if the rule is a look rule; false otherwise

isTaskRule

public boolean isTaskRule()

Indicates that a rule involves the assignment of a task.

Returns:

true if the rule is a task rule; false otherwise

isEntityRule

public boolean isEntityRule()

Indicates that a rule involves the assignment of an entity.

Returns:

true if the rule is an entity rule; false otherwise

isEntityPermissionRule

public boolean isEntityPermissionRule()

Indicates that a rule involves the assignment of an entity permission.

Returns:

true if the rule is an entity permission rule; false otherwise